Linear conveyor, conveyance carriage, and drive control method for linear conveyor

Abstract

A linear conveyor includes: a linear motor stator which includes a plurality of electromagnets and in which each predetermined section can be individually controlled for conduction; a plurality of conveyance carriages each of which includes a linear motor mover; a linear scale which includes scale members secured to each of the conveyance carriages, and detectors disposed along a conveyance path; a plurality of motor controllers which individually controls conduction of electromagnets for each section based on the results of detecting the scale members by the detectors; and a data storage unit which stores position correction data for each conveyance carriage, determined based on the movement error of each conveyance carriage measured in advance using a common measurement jig. Each motor controller controls conduction of the electromagnets using the position correction data stored in the data storage.

The invention claimed is: 
     
       1. A linear conveyor, comprising:
 a linear motor stator which includes a plurality of electromagnets arranged along a predetermined conveyance path, and in which each section of said predetermined conveyance path is individually controlled for conduction; 
 a first conveyance carriage and a second conveyance carriage each including a linear motor mover which is a permanent magnet and constitutes a linear motor in tandem with a linear motor stator, the conveyance carriages being movably disposed along the conveyance path; 
 a linear scale which includes scale members secured to each of the conveyance carriages, and detectors disposed along the conveyance path so that the scale members are detected; 
 a plurality of motor controllers which are disposed in correspondence with the sections of the linear motor stator respectively, and individually control conduction of the electromagnets for each section based on the results of detecting the scale member by the detector; 
 a first data storage unit which stores position correction data determined based on a movement error unique to the first conveyance carriage that occurs due to an assembly error of the first conveyance carriage including an installation position error of the scale member, the movement error of the first conveyance carriage being obtained by means of a measurement jig which includes a data acquisition stator having a configuration identical to the section of the linear motor stator, a data acquisition detector having a configuration identical to the detector, and which is used to control conduction of electromagnets of the data acquisition stator based on a detection result of the scale member obtained by the data acquisition detector to thereby move the first conveyance carriage along a conveyance path for the data acquisition stator and measure a position of the first conveyance carriage to obtain, based on a measurement result, the unique movement error of the first conveyance carriage, and 
 a second data storage unit which stores position correction data determined based on a movement error unique to the second conveyance carriage that occurs due to an assembly error of the second conveyance carriage including an installation position error of the scale member, the movement error of the second conveyance carriage being obtained by using the measurement jig to control the conduction of the electromagnets of the data acquisition stator based on a detection result of the scale member obtained by the data acquisition detector to thereby move the second conveyance carriage along the conveyance path for the data acquisition stator and measure a position of the second conveyance carriage to obtain, based on a measurement result, the unique movement error of the second conveyance carriage, wherein 
 each of the plurality of motor controllers determines, as control data, either the position correction data stored in the first data storage unit or processed data obtained through processing using the position correction data, and controls the conduction of the electromagnets using the control data, so as to stop the first conveyance carriage at a target stopping point, and determines, as control data, either the position correction data stored in the second data storage unit or processed data obtained through processing using the position correction data, and controls the conduction of the electromagnets using the control data, so as to stop the second conveyance carriage at a target stopping point. 
 
     
     
       2. The linear conveyor according to  claim 1 , wherein
 each of the motor controllers includes the first data storage unit and the second data storage unit, and 
 each of the motor controllers controls the conduction of the electromagnets using the position correction data stored in the respective first and second data storage units. 
 
     
     
       3. The linear conveyor according to  claim 1 , wherein
 the first conveyance carriages includes a first storage medium storing the position correction data of the first conveyance carriage, 
 the second conveyance carriage includes a second storage medium storing the position correction data of the second conveyance carriage, 
 the linear conveyor further comprises a reading unit which reads the position correction data stored in the storage medium of each conveyance carriage, 
 the first data storage unit stores the position correction data of the first storage medium read by the reading unit, and
 the second data storage unit stores the position correction data of the second storage medium read by the reading unit. 
 
 
     
     
       4. The linear conveyor according to  claim 1 , further comprising a plurality of unit members each of which includes a rail member for forming the conveyance path, and the electromagnets arranged along the rail member respectively, wherein
 the conveyance path is formed by the rail members and the linear motor stator is formed of electromagnets by the unit members that are linked in series in the longitudinal direction of the rail members, and 
 each of the motor controllers controls the conduction of the electromagnets included in each of the unit members as one section of the linear motor stator. 
 
     
     
       5. A conveyance carriage that constitutes a linear conveyor in tandem with a conveyor composing member by being installed on a rail member of the conveyor composing member that includes: the rail member which forms a conveyance path; a linear motor stator which includes a plurality of electromagnets arranged along the rail member and in which each predetermined section is individually controlled for conduction; a detector disposed along the conveyance path so that a predetermined scale member is detected; a reading unit that reads data stored in a predetermined storage medium; and a plurality of motor controllers which are disposed in correspondence with the respective sections of the linear motor stator, and individually control conduction of the electromagnets for each section based on control data, which is either the data read by the reading unit or data obtained through processing using the data and the result of detecting the scale member by the detector, the conveyance carriage comprising:
 a frame member which is movably installed on the rail member; 
 a linear motor mover which is a permanent magnet secured to the frame member, and constitutes a linear motor in tandem with the linear motor stator; 
 the scale member which is secured to a position, in the frame member, that is detected by the detector, and which constitutes a linear scale in tandem with the detector; and 
 the storage medium secured to the frame member, wherein 
 the storage medium stores position correction data determined based on a movement error unique to the conveyance carriage that occurs due to an assembly error of the conveyance carriage including an installation position error of the scale member, the movement error being obtained by means of a measurement jig which includes a data acquisition stator having a configuration identical to the section of the linear motor stator, a data acquisition detector having a configuration identical to the detector, and a position measuring device, and which is used to control conduction of electromagnets of the data acquisition stator based on a detection result of the scale member obtained by the data acquisition detector to thereby move the conveyance carriage along a conveyance path for the data acquisition stator and measure a position of the conveyance carriage to obtain, based on a measurement result, the unique movement error of the conveyance carriage. 
 
     
     
       6. A drive control method for a conveyance carriage of a linear conveyor that includes: a linear motor stator which includes a plurality of electromagnets arranged along a predetermined conveyance path, and in which each predetermined section is individually controlled for conduction; a first conveyance carriage and a second conveyance carriage each including a linear motor mover which is a permanent magnet, and movably disposed along the conveyance path; and a linear scale which includes scale members secured to the conveyance carriages respectively, and detectors disposed so that the scale members are detected, the drive control method comprising:
 a first data acquisition step of using a measurement jig which includes a data acquisition stator having a configuration identical to the section of the linear motor stator, a data acquisition detector having a configuration identical to the detector, and a position measuring device, to control conduction of electromagnets of the data acquisition stator based on a detection result of the scale member obtained by the data acquisition detector to thereby move the first conveyance carriage along a conveyance path for the data acquisition stator and measure a position of the first conveyance carriage to obtain, based on a measurement result, a movement error unique to the first conveyance carriage that occurs due to an assembly error of the first conveyance carriage including an installation position error of the scale member; 
 a second data acquisition step of using the measurement jig to control the conduction of the electromagnets of the data acquisition stator based on a detection result of the scale member obtained by the data acquisition detector to thereby move the second conveyance carriage along the conveyance path for the data acquisition stator and measure a position of the second conveyance carriage to obtain, based on a measurement result, a movement error unique to the second conveyance carriage that occurs due to an assembly error of the second conveyance carriage including an installation position error of the scale member; and 
 a conveyance carriage moving step of moving, in the linear conveyor, each of the conveyance carriages by individually controlling conduction of the electromagnets for each section based on results of detecting the scale members by the detectors using motor controllers which are disposed in correspondence with the respective sections of the linear motor stator, wherein 
 the conveyance carriage moving step includes:
 a first conveyance carriage moving step of determining either the movement error data acquired in the first data acquisition step or processed data obtained through processing using the movement error data as control data, and causing the motor controller to control conduction of the electromagnets using the control data to thereby move the first conveyance carriage; and 
 a second conveyance carriage moving step of determining either the movement error data acquired in the second data acquisition step or processed data obtained through processing using the movement error data as control data, and causing the motor controller to control conduction of the electromagnets using the control data to thereby move the second conveyance carriage.